package com.hit.basmath.learn.linked_list;

import com.hit.common.ListNode;

/**
 * 21. Merge Two Sorted Lists
 * <p>
 * Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.
 * <p>
 * Example:
 * <p>
 * Input: 1->2->4, 1->3->4
 * Output: 1->1->2->3->4->4
 */
public class _21 {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if (l1 == null) return l2;
        if (l2 == null) return l1;
        if (l1.val < l2.val) {
            l1.next = mergeTwoLists(l1.next, l2);
            return l1;
        } else {
            l2.next = mergeTwoLists(l1, l2.next);
            return l2;
        }
    }
}
